Chapter 2. Adjusting Timing Tables and Calibrating Color

Timing tables determine important characteristics that control your 1600SW flat panel monitor. Unlike CRT monitors, the 1600SW flat panel monitor supports only one resolution, 1600 pixels wide by 1024 pixels tall. However, you can adjust the refresh rate of your panel. This is explained in “Adjusting the Flat Panel Monitor's Refresh Rate” below.

This chapter also explains how to calibrate the Silicon Graphics 1600SW flat panel monitor when it is attached to an O2 workstation. See “Calibrating the Flat Panel Monitor With the ColorLock Sensor”.

Adjusting the Flat Panel Monitor's Refresh Rate

The refresh rate is a measure of the number of times the screen is drawn to the flat panel in one second and it is measured in Hertz (Hz). The default refresh rate for the 1600SW flat panel monitor is 50 Hz. This setting works very well for most applications. If you need to display NTSC video, however, you should use the 60 Hz timing table to ensure the proper NTSC frame rate. The 48 Hz table may be useful for the film industry.

Because the 1600 SW flat panel monitor is an all-digital device, there is no screen flicker visible in any of the timing tables provided. In IRIX 6.5.2 or later, you can change monitor timings using the Xsetmon command.

To start Xsetmon, follow these steps:

  1. From the Toolchest, choose System > Display Properties.

    When Xsetmon starts, you see a screen similar to what is shown in Figure 2-1.

    Figure 2-1. Xsetmon Main Screen

  2. To change the monitor timing, select one of the timing formats in the Valid Formats window, and click Load. Note the following:

    • The refresh rate appears in the timing table name following the _ character. For example, 1600x1024_60p indicates a refresh rate of 60 Hz.

    • Flat panel settings have a “p” suffix.

    • Unlike conventional CRT monitors, the fastest possible timing is not always the most desirable for your application. The flat panel monitor should be flicker-free at any of the timings (48 Hz, 50 Hz, and 60 Hz). The O2 system software default for the 1600SW flat panel monitor is 50 Hz.

    • When displaying NTSC video, select the 60 Hz timing table (1600x1024_60p).

Caution: When using 60 Hz timing, change your desktop background to Solid to keep spurious lines from appearing on your screen. These lines are the result of an interaction between the monitor timing and the workstation graphics subsystem, and appear only with complex backgrounds and the 60 Hz timing table. To change your background, from the Toolchest choose Desktop > Customize > Background.

About the Gamma Settings in Xsetmon

Do not change the gamma setting of your flat panel monitor with Xsetmon. Use the 1600SW Flat Panel's Settings Control Panel to change the gamma, as described in “Changing the Gamma”.

Using the 1600SW Flat Panel Settings Control Panel

The 1600SW flat panel monitor features ColorLock technology, an integrated color calibration system. Your O2 workstation's system software includes a special control panel with which you adjust color temperature, intensity, and gamma.

If you are not familiar with color calibration software, you may want to skip to the Glossary on page 53, before reading this chapter.

You can adjust various flat panel monitor settings, including the color temperature, intensity (brightness), and gamma with the Flat Panel Settings control panel (Figure 2-2). You can also use the control panel to calibrate your monitor to achieve the most accurate settings possible.

Note: Always use the Screen Saver program with the Power Saver option selected. Using these features dramatically prolongs the life of the backlights in the flat panel monitor and prevents images from burning into the screen.

Figure 2-2. 1600SW Flat Panel Settings Control Panel

There are several ways to start the Flat Panel Settings control panel (Figure 2-2):

  • From the Toolchest, choose Desktop > Customize > Flat Panel.

  • From the Toolchest, choose Find > ControlPanels and double-click the fp_1600sw icon.

  • In a shell window, enter /usr/sbin/flatpanel

You may begin adjusting the parameters for gamma, color temperature, and intensity at any time. While calibration with the ColorLock sensor is not required for these adjustments, the ColorLock technology built into your panel works best when you calibrate using the ColorLock sensor. Depending on usage, you should only have to recalibrate approximately once every two months.

In a multi-user environment, each user should calibrate the panel for their environment, particularly if the room lighting or other working conditions differ between users. See “Calibrating the Flat Panel Monitor With the ColorLock Sensor”. Also, each user account can have a different set of presets. Presets allow you to group favorite combinations of gamma, color temperature, and intensity together for quick adjustments. See “Creating and Saving Presets”.

Calibrating the Flat Panel Monitor With the ColorLock Sensor

With your adapter kit you received a ColorLock sensor. Calibration with the ColorLock sensor adjusts your settings more accurately, taking into account your panel's age and other environmental factors.

Note: No universal system for color calibration exists, because the human visual system is complex and difficult to model. The 1600SW flat panel monitor received specialized factory calibration during manufacture. With data stored in the panel and ColorLock sensor calibration procedures, you can adjust the color temperature accurately. Additionally, you can achieve precise gamma settings.

Tip: For the most accurate results, choose the color temperature and intensity settings before calibrating. However, you can always adjust these parameters following a calibration.

Tip: To calibrate the flat panel monitor, follow these steps:

Figure 2-3. Calibrate Flat Panel Window

  1. From the Flat Panel Settings control panel, click Calibrate. (See Figure 2-2.) The flat panel calibration window appears, as shown in Figure 2-3.

    Figure 2-4. Attaching the ColorLock Sensor to the Flat Panel Monitor

  2. Attach the ColorLock sensor to the flat panel monitor, as shown in Figure 2-4.

    • Use both hands to lay the sensor over the top of the monitor, hooking it over the edge of the frame. Be careful not to scratch the flat panel screen.

    • Place the rounded end of the sensor over the center of the Calibration Window. Do not move the calibration window, because the calibration procedure is designed to work best when the window and sensor are at the center of the screen.

    • Make sure the sensor snaps into one of the vent holes on the back of your monitor.

      Figure 2-5. Connecting the ColorLock Sensor Cable to the Flat Panel Monitor

  3. Plug the sensor cable into the sensor port on the back of the flat panel (next to the power port), as shown in Figure 2-5. The sensor port looks like an ordinary headphone jack.

  4. Click OK to begin calibrating. The automated procedure displays various colors and diagnostic messages as it progresses. To stop the calibration process, click Cancel at any time. When the calibration cycle is complete, the calibration window disappears.

    Note: Although the flat panel monitor's gamma, color temperature, and intensity settings are altered during the automated calibration procedure, your last settings will be restored (with increased accuracy) as soon as the procedure completes.

  5. To remove the ColorLock sensor, use both hands. Lift the back of the sensor away from the vent holes with one hand, and lift the front of the sensor away from the flat panel screen with the other hand.

Changing the Color Temperature (White Point)

Color temperature refers to the definition of the flat panel monitor's white point. The definition of the color white is not absolute, and may exist somewhere in color space from red-white to blue-white. You may adjust the white point within this red-blue range.

Your 1600SW flat panel monitor is capable of color temperature adjustments between 5000 degrees and 7000 degrees Kelvin. The ColorLock technology, however, may be able to adjust to a wider temperature range, especially with a new flat panel monitor, or following a ColorLock sensor calibration.

To change the color temperature (white point) of the monitor, in the 1600SW Flat Panel Settings window, move the Color Temperature slider right or left. The color temperature indicated above the slider changes as you move the slider.

You can move the slider in 100-degree increments by clicking on the part of the slider display to the left or right of the slider button (called the “well.”)

Changes to the color temperature are visible immediately, but changes are not saved until you click Apply. For more information, see “Creating and Saving Presets”.

Note: Whenever you change the color temperature slider, the intensity slider automatically jumps to 100, because the software automatically picks the brightest intensity available at the selected color.

Changing the Intensity (Brightness)

Intensity specifies the luminance (or brightness) of colors on the flat panel monitor. Intensity is a relative measure and depends on your settings for gamma and color temperature.

To change the intensity (or brightness) of the monitor, use the Intensity slider in the 1600SW Flat Panel Settings window. Moving the slider to the right increases the intensity and to the left decreases the intensity.

Move the slider in 10-unit increments by clicking on the part of the slider display to the left or right of the slider button (called the “well.”) Be aware that whenever you change the color temperature, the intensity slider automatically moves up to 100.

The intensity varies between 0 (lowest available) and 100 (maximum available). Changes to the intensity are visible immediately, but are not saved until you click Apply. See “Creating and Saving Presets”.

Note: You may notice that maximum intensity varies in overall brightness depending upon color temperature selection. This is completely normal.

Changing the Gamma

The gamma of a display describes the relationship between the video input signal level and the light output or intensity displayed on the monitor. The 1600SW flat panel monitor has a native (or uncorrected) gamma value of 1.8. Based on your work environment and how you use your monitor, you may want to choose a different gamma value. The gamma setting can be varied between 1.0 and 3.0.

Caution: Use only the Flat Panel Settings control panel to change the gamma, as described below. Do not use Xsetmon or the IRIX gamma command.

To change the gamma of the 1600SW flat panel monitor, follow these steps:

  1. In the 1600SW Flat Panel Settings control panel, enter the desired gamma value in the selection box.

  2. Highlight the existing value and type in a new value.

  3. Click Apply to see the effect of the gamma change and to save the change to the current preset. See “Creating and Saving Presets”.

    The gamma setting adjusts desired (or system) gamma. See the Glossary on page 53 for further explanation.

Creating and Saving Presets

Each user account on a multiuser workstation can have a different set of flat panel monitor presets. Presets are stored in $HOME/.Sgiresources.

To create a preset of various color settings, follow these steps:

  1. In the 1600SW Flat Panel Settings control panel, click New.

  2. In the dialog box, enter the name of your preset and click OK.

  3. Make any changes to the gamma, color temperature, and intensity.

  4. Click Apply to save the changes to your preset.

Notice that your preset is now visible in the list of presets in the settings control panel. The preset name that is active at the time you click Close is selected the next time you use the control panel. To load a preset automatically whenever you log in, see “Loading Presets Automatically.”

Note: You may only create unique preset names. If you enter an existing preset name in the New Preset dialog, you are asked to choose another preset name. Only alphabetic characters are allowed; other characters are removed.

Loading Presets Automatically

Each user account on a multiuser workstation can be set up to load a preset automatically upon beginning an X session. To enable this feature, place the following line in the $HOME/.sgisession file of each user account on the system:

/usr/sbin/flatpanel -nogui

The last active preset will be loaded whenever you log into an account configured in this manner. If you do not add the above line to each user's $HOME/.sgisession file, you will need to run the 1600SW flat panel monitor Settings control panel manually with the start of each new X session.

Removing Presets

To delete a preset, edit the $HOME/.Sgiresources file and remove all references to that preset name. To return to factory settings, remove all references to the preset Default.

Caution: The .Sgiresources file may contain settings from other applications. Use care when deleting this file entirely, as you may affect other programs.

Using Screen Savers

You should always use the Screen Saver program with the Power Saver option selected to prolong the life of your backlights and reduce the need for frequent recalibration with the ColorLock sensor.

Caution: The O2 workstation's PROM has no screen saver or power saver function. If you plan to leave the O2 PROM running for an extended period of time, be sure to turn off the 1600SW flat panel monitor. For example, you might start a miniroot installation, and leave it running overnight.

Note: The login screen saver is not affected by the Screen Saver settings of any user including root. It is recommended that you edit the file /var/X11/xdm/Xlogin. Look for the line that includes the command

if [ -x /usr/bin/X11/xset ] ; then
/usr/bin/X11/xset s [seconds] [seconds]

Alter both arguments in the second line to one-half the values shown. For example,

if [ -x /usr/bin/X11/xset ] ; then
/usr/bin/X11/xset s 600 1200


if [ -x /usr/bin/X11/xset ] ; then
/usr/bin/X11/xset s 300 600

See the xset man page for more details.